1. Field of the Invention
The present invention relates, in general, to watthour meters and, more specifically, to adapters for mounting a watthour meter to a support surface.
2. Description of the Art
Electrical watthour meters have long been used to measure the amount of electrical power consumed by an electrical utility customer. Watthour meters have been constructed in various configurations depending upon the type of electrical service that is required.
Older style watthour meters of the so-called bottom connected type are formed of a single piece housing containing internal power measurement elements, externally visible gages and bottom mounted terminals which provide connection between the external electrical utility power line conductors and the building load distribution network.
Several types of bottom-connected watthour meters are shown in FIG. 1. The upper three watthour meters are OB type watthour meters and have a relatively small current capability, such as ten amps. This results in a small overall exterior size for an OB watthour meter. The housing of an OB watthour meter includes a cylindrical portion containing the meter power measurement elements and the gages, and a bottom extending terminal portion containing internally mounted terminals which receive the line and load conductors. A terminal cover is removably mountable over the terminal portion to cover the terminal connections,
Although modern power requirements have resulted in larger amperage watthour meters, the smaller OB watthour meters still remain in use. FIG. 1 depicts a typical mounting arrangement of a plurality of OB watthour meters used, for example, in an apartment building. Due to the small size of the OB watthour meters, a plurality of OB watthour meters can be mounted on a wall or support surface in a vertical column in close proximity to each other.
When it becomes desirable or necessary to increase the amperage supplied to a particular distribution load, or to replace a failed OB watthour meter, a watthour meter having a higher current rating, such as a modern, plug-in type watthour meter is typically employed. However, such plug-in watthour meters, as depicted in the bottommost watthour meter in FIG. 1, have a considerably larger overall diameter and size than the smaller OB type watthour meters. In order to mount a plug-in watthour meter to the support surface, a watthour meter socket adapter, such as that shown in U.S. Pat. No. 5,207,595, assigned to the assignee of the present invention, is employed. This type of watthour meter provides bottom terminal connections in the same manner as in the OB type watthour meter.
However, the larger diameter of the watthour meter receiving portion of the socket adapter which is necessary to receive the larger diameter plug-in watthour meter, and the bottom extending terminal portion of the socket adapter which carries the terminal connections to the external line and load conductors is frequently too large to be easily installed between two spaced OB watthour meters in a vertical column.
Another problem encountered during replacement of an OB watthour meter results from the long length of service or age of such OB watthour meters. The line and load conductors connected to the OB watthour meter become brittle over long use such that any excessive movement or bending of such conductors to reattach the conductors to a new watthour meter or watthour meter socket adapter frequently results in breakage of the conductors or disintegration of the insulation on the conductors. This may pose a significant environmental problem since older style conductors frequently employed asbestos insulation.
Thus, it would be desirable to provide a watthour meter adapter which has a smaller overall outer dimensional shape than previously devised watthour meter adapters. It would also be desirable to provide such a watthour meter adapter which can be used to replace a bottom connected watthour meter with a modern plug-in watthour meter. It would also be desirable to provide such a watthour meter adapter which enables the existing line and load conductors to be reconnected to the terminals in the adapter without excessive bending or movement of such conductors.